import java.io.BufferedReader;
import java.io.InputStreamReader;


public class Main {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		int i = 1, count = 0;
		while(true) {
			int j = i;
			if(i * j > n) {
				break;
			}
			while(true) {
				if(i * j > n) {
					break;
				}
				count++;
				j++;
			}
			i++;
		}
		System.out.println(count);
	}
}
